The present invention relates to a new and distinctive creeping bentgrass (Agrostis palustris (stolonifera)), a variety used primarily as commercial golf course turf.
There are over 100 species of Bentgrass (Agrostis) but only two are used to any great extent as golf course turf. Bentgrass is well adapted to close mowing due to its prostrate growth habit. They grow best in moist uncompacted soils and have broad temperature hardiness.
The Agrostis genus—better known as the bentgrasses—is comprised of over 100 species, several of which have been developed into successful turfgrasses. One Agrostis in particular, A. stolonifera or creeping bentgrass, has become the preeminent grass for golf course putting greens the world over. Another Agrostis species, colonial bentgrass (A. tenuisSibth.), has been bred into a golf course grass useful on tees and fairways in cooler regions. Two or three other Agrostis species find minor turf application, mostly for golf, tennis courts, bowling greens, or an occasional home lawn.
The Agrostis genus is widely distributed throughout the world with representative species found on all of the northern continents. However, of the present-day bentgrass species in use as turfgrasses, all originated from Europe. The original seed of these plants was brought to the US during colonial times.
America has an abundance of native bentgrass species (A. S. Hitchcock, 1951, Manual of the grasses of the United States. USDA Misc. Publ. 200) but none are commercially useable as turf grass.
Creeping bentgrass (Agrostis palustris) is so named due to its ability to creep laterally by stolons. The stolons are able to root at the nodes producing a new plant. Creeping bentgrass is the plant of choice for fairways, tees and greens where the height of cut is below one-half inch.
Creeping bentgrass (Agrostis palustris) is a perennial cool season grass that forms a dense mat. The grass spreads by profuse creeping stolons and basal tillers and possesses rather vigorous, shallow roots. Stems, or stolons, are decumbent (creeping) and slender and produce long narrow leaves. Leaf blades are smooth on the upper surface and ridged on the underside, are approximately 1 to 3 mm wide and bluish green in appearance. The ligule is long, membranous, finely toothed or entire and rounded, auricles are absent.
Developing new grass species is difficult, time consuming, and expensive. The developer must sift through thousands of prospective grasses listed in botanical literature, identify promising grasses, and often travel thousands of miles to locate, isolate, identify, transport, quarantine, grow, test, and breed these grasses. This process can take more than 10 years to develop acceptable cultivars. Furthermore, as it turns out, most prospective grasses in nature have no commercial turf value, due to their inability to generate an acceptable ground cover when mowed. The vast majority of natural grasses cannot produce a plush lawn under continuing defoliation.
Yet another complexity facing the plant developer is the unresponsiveness of many wild grasses to plant breeding. The vast majority of wildland grasses lack genetic potential for refinement into desirable turfgrass cultivars. Only after considerable investment in collection and breeding does the developer discover which grass species can be successful bred and which cannot.
The development of new turf grasses requires the development and selection of bentgrass varieties, the crossing of these varieties and selection of superior hybrid crosses. The hybrid seed is produced by manual crosses between selected male-fertile parents or by using male sterility systems. These hybrids are selected for certain single gene traits such as pod color, flower color, pubescence color or herbicide resistance which indicate that the seed is truly a hybrid. Additional data on parental lines, as well as the phenotype of the hybrid, influence the breeder's decision whether to continue with the specific hybrid cross.
Pedigree breeding and recurrent selection breeding methods are used to develop cultivars from breeding populations. Breeding programs combine desirable traits from two or more cultivars or various broad-based sources into breeding pools from which cultivars are developed by selfing and selection of desired phenotypes. The new cultivars are evaluated to determine which have commercial potential.
Pedigree breeding is used commonly for the improvement of self-pollinating crops. Two parents that possess favorable, complementary traits are crossed to produce an F1. An F2 population is produced by selfing one or several F1's. Selection of the best individuals may begin in the F2 population; then, beginning in the F3, the best individuals in the best families are selected. Replicated testing of families can begin in the F4 generation to improve the effectiveness of selection for traits with low heritability. At an advanced stage of inbreeding (i.e., F6 and F7), the best lines or mixtures of phenotypically similar lines are tested for potential release as new cultivars.
Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.
Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or inbred line which is the recurrent parent. The source of the trait to be transferred is called the donor parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.
The single-seed descent procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one-seed sample to plant the next generation. When the population has been advanced from the F2 to the desired level of inbreeding, the plants from which lines are derived will each trace to different F2 individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F2 plants originally sampled in the population will be represented by a progeny when generation advance is completed.
In a multiple-seed procedure, bentgrass breeders commonly harvest one or more panicles from each plant in a population and thresh them together to form a bulk. Part of the bulk is used to plant the next generation and part is put in reserve. The procedure has been referred to as modified single-seed descent or the panicle-bulk technique.
The multiple-seed procedure has been used to save labor at harvest. It is considerably faster to thresh panicles with a machine than to remove one seed from each by hand for the single-seed procedure. The multiple-seed procedure also makes it possible to plant the same number of seeds of a population each generation of inbreeding. Enough seeds are harvested to make up for those plants that did not germinate or produce seed.
Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Allard, 1960; Simmonds, 1979; Sneep et al., 1979; Fehr, 1987).
Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer; for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.